Polyester resin based on a tetracarboxylic acid



United States Patent 3,108,085 PULYESTER RESIN BASED ON A TETRA- CARBQXYLI ACID Ronald L. Eroadhead, Park Forest, llL, assignor to Stand- 3rd Uii Company, Qhicago, Ill., a corporation of Inrana No Drawing. Filed Apr. 29, 1960, Ser. No. 25,548 11 Claims. (ill. 26ll2.2)

This invention relates to resins of the polyester condensation reaction type and particularly resins which are suitable for the formation of an air-dry surface coating film, and preferably, resins which have substantial solubility in water.

Resins have been used for a long time in the production of surface coating films. The so-called alkyd resins which are extensively used for production of surface coatings possess reasonable air-dry properties at ordinary atmospheric temperatures. (The term air-dry means the ability of the resin to form a rigid solid film when exposed to the atmosphere at ordinary temperatures, particularly 50-100 F.) These alkyd resins are soluble in hydrocarbon solvents.

Extensive efforts have been made to produce materials suitable for surface coating application which materials can use water as the vehicle. At present, air-dry surface coatings are producible only by the use of true emulsions or latex emulsions when water is the vehicle. For reasons of flexibility in formulation and storage stability, a truly water soluble surface coating system is of very great interest to the paint industry.

A resin suitable for the formation Of an extremely hard air-dry surface coating film has been discovered which resin is soluble in the ordinary hydrocarbon solvents and oxygenated organic solvents now used in the paint industry and is also capable of forming very stable emulsions with Water as the paint vehicle. A truly water soluble resin suitable for the formation of an airdry surface coating film and low viscosity solution has been discovered; this water soluble resin is the reaction product of the organic solvent soluble resin and a hereinafter defined amine or ammonia.

The air-dry properties of the resins of the invention are to be understood as indicating that when a surface coating film-for example, 1 mil thick-4s formed from organic solvent solution or water solution or water emulsion, the film will harden and form a solid structure such as afforded by present air-dry paints. The time needed to form a tackfree film will vary with the particular resin, the temperature to which the film is exposed, and the presence or absence of driers. The presence of cobaltdriers such as normally utilized in the paint industry permits the formation of hard-tack-free films in periods of time permitting use on exterior and interior surfaces.

RESIN The organic solvent soluble resin of the invention consists essentially of the polycondensation reaction product of a benzene tetracarboxylic acid, polyal kylene glycol monoalkyl ether, a monoglyceride type product of a polyunsaturated fatty acid and glycerol or an erythritol, or an alcoholysis product of drying fatty oils with glycerol or an erythn'tol which alcoholysis product cor-responds on the average to a monoglyceride type compound and a phthalic acid or phthalic anhydride. Also, the resin can be prepared by utilizing a polyunsaturated fatty alcohol in addition to the monoglyce-ride or alcoholysis product.

The tetrac-arboxylic acid reactant is an acid or anhydride having the following configuration:

G (HOOD y (COOH):

wherein x is an integer from 1 to 3, y is an integer from 1 to 3, and x and y equal 4; n is an integer from O to l and Z is selected from the class consisting of CO, and alkyl containing from 1 to 5 carbon atoms. R is preferred that each benzene ring contain 2 carboxylic groups or the anhydride grouping. Acids containing CH or CH3-C-CH3 or the CO group as Z are particularly suitable. Illustrative tetnacanboxylic acids are:

3,3',4,4-b=enzophenone tetnacarb-oxylic acid (or anhydbide) 2,2,4,4,-benzophenone tetracanboxylic acid 2,2',3,3-benzophenone tetracarboxylic acid (or anhydride) 3,3,4,4-diphenylmethane-tetracarboxylic acid (or anhydride) 2,2,4,4-diphenylmethanetetracarboxylic acid 2,2',3,3'-diphenylmethane-tetracarboxylic acid (or anhydride) The tetracarboxylic acid is reacted with polyalkylene glycol monoalkyl ether. This ether contains from 2 to 8 ether groups; each alkylene unit present in the ether contains from 2 to 3 carbon atoms, i.e., the alkylene units are either ethylene or propylene; the \alkyl group present in the ether contains from 1 to 8 carbon atoms. Numerous species of the defined ethers are available commercially under the Car-bitol trade name. The Carbitols are alkylation reaction products of ether glycols and alkanols. Illustrative ether glycols are diethylene glycol, triethylene glycol, tetraethylene glycol, and polyethylene glycols containing not more than 8 ether linkages; dipropylene glycol, tripropylene glycol, and polypropylene glycols containing not more than 8 ether linkages. Illustrative alkanols are methanol, ethanol, isopropanol, n-butanol, tbutyl alcohol, and octanol. The mixtures of isomeric alkanols prepared :by the 0x0 process are particularly suitable, especially isooctyl alcohol. To illustrate the nomencature utilized herein: The alkyl-ation product of diethyene glycol with ethanol is known as diethylene glycol monoethyl ether, or 2-(2-ethoxyethoxy)ethanol, or ethylcarbitol.

The ester of the defined itetracarhoxylic acid and the defined ether (and hereinafter defined fatty alcohol) is con densed in a polyesterification condensation reaction with :a material affording two hydroxyl groups per molecule. This hydroxyl group affording material may provide two hydroxyl groups per molecule only as an average of the molecules in the material. When this material is an alcoholysis product, there may be on the average somewhat more than two hydroxyl groups per molecule. This material in elfect functions as a dihydric alcohol.

The dihydroxyl group affording material may be an ester of a polyethenoid fatty acid containing at least about 10 carbon atoms and a polyhydric paraffinic alcohol (alkane polyol) containing 3-4 hydroxyl groups. The polyhydric alcohol-s include glycerol, erythritol, pentaerythritol, threitol, dipentaerythritol, and trimethylol propane. The polyethenoid fatty acid contains at least two olefinic bonds and contains at least about 10 carbon atoms. The fatty acids containing l624 carbon atoms are particularly suitable. Illustrative fatty acids are: linoleic, hiragonic, eleostearic, moroctic, arachidonic, clupanodonic, and nisinic. Economical and preferred sources of acids are the natural mixtures of acids obtained from drying fatty oils such as linseed oil, soya oil, tung oil, etc.

When the defined polyol is glycerol, the ester charged to the reaction zone is properly termed a monoglyceride of the particular fatty acid. For convenience, the terminology monoglyceride is utilized to describe this ester even when the polyol utilized in the formation of the ester is some other three of four hydroxyl group containing polyol.

Instead of more or less pure monoglyceride, the dihydroxyl group affording material may be the alcoholysis product of the hereinabove defined polyol and a drying fatty oil. When the polyol used in the alcoholysis reaction is glycerol, then the alcoholysis product will include the monoglyceride of the polyethenoid fatty acids contained in the drying oil and also of the other fatty acids contained in the drying oil and also the non-reactive materials. When the reacting polyol is other than glycerol, the alcoholysis product will include a mixture of true glycerides and glyceride type esters of the various acids and the reacting polyol. Sufficient reacting polyol is utilized in the alcoholysis reaction to have in the alcoholysis product compounds affording on the average two hydroxyl groups per molecule.

Any of the drying oils containing polyethenoid fatty acid esters, whether of vegetable or marine life origin, may be utilized. Illustrative of these drying oils are: linseed, soybean, tung, castor, dehydrated castor, oiticica, perilla, safflower, menhaden, and sardine.

When special properties are desired, the dihydroxyl group affording material may be a mixture of one or more of the various monoglycerides or a mixture of monoglyceride with an alcoholysis product or a mixture of alcoholysis product from two or more fatty oils, etc.

Particularly suitable air-drying resins are obtained when utilizing monoglycerides of linseed oil fatty acids, the alcoholysis product of linseed oil fatty acids with either glycerol or pentaerythritol, the monoglycerides of tung oil fatty acids and the alcoholysis product of tung oil with pentaerythritol.

An air-dry resin can be obtained by reacting the ester product of the defined tetracarboxylic acid and defined ether with a polyethenoid fatty alcohol containing at least 6 carbon atoms, or an ester product of simultaneously reacting the tetracarboxylic acid, the ether, and the fatty alcohol with the hereinabove defined dihydroxyl group affording materials. The polyethenoid fatty alcohol contains at least two olefinic bonds and at least 6 carbon atoms. The fatty alcohols containing from 16 to 24 carbon atoms are particularly suitable. In addition to pure fatty alcohols, the fatty arcohols derived by the controlled hydrogenolysis of drying fatty oils may be used and, indeed, are the preferred sources of fatty alcohol.

The ester product containing the fatty alcohol is then condensed with the hereinabove defined dihydroxyl group affording materials in the same manner and in the same ratios as When no fatty alcohol was used.

The polycondensation product resin is a material characterized by an acid number of about -60 (acid numer is the mg. KOH per gram of resin), preferably -50. Also, this resin is characterized by air-drying properties when exposed to the atmosphere at ordinary temperatures in the form of a surface coating film.

In order to give utmost clarity, the relative amounts of each reactant charged to the resin preparation are set out hereinafter as the molar amount charged when the molar amount of tetracarboxylic acid charged is one (1).

The defined ether is charged in an amount of from at least about 0.35 to about 1.0 mole.

No fatty alcohol need be charged. The amount of fatty alcohol charged may be from none, i.e. zero, to about 1.65 mole; but the sum of the amount of ether charged and the amount of fatty alcohol charged may not be more than double the molar amount of tetracarboxylic acid charged. Thus when the ether usage is 1.0, the maximum fatty alcohol usage is 1.0; and when the ether usage is 0.5, the maximum fatty alcohol usage is 1.5.

The two hydroxyl group affording material is charged in an amount sufficient to provide an excess of hydroxyl groups over free-carboxyl groups present. This amount is from about not less than 0.5 mole of hydroxyl groups to not more than about 1 mole of hydroxyl groups per mole of tetracarboxylic acid charged. The theoretical requirement is calculated as one mole of hydroxyl groups from said dihydroxyl material for each mole of carboxyl groups from said tetracarboxylic acid less the hydroxyl groups provided by said ether (and said alcohol).

he ester preparation reaction is carried out by intermingling the tetracarboxylic acid member and the ether (and the fatty alcohol) at a temperature on the order of -130 C. until all of the acid has passed into solution, i.e., reacted. When the fatty alcohol ester is desired, the tetracarboxylic acid and the other may be reacted under these temperature conditions and then the fatty alcohol added and the reaction continued until the alcohol has passed into solution, i.e., reacted. The reaction is carried out utilizing a reflux system permitting trapping-out of the Water formed in the reaction.

The polycondensation reaction is carried out in the usual manner. The reaction herein has usually been carried out in a vessel provided with a condensing system permitting trapping-out of water of reaction. The reac-tants are agitated at a temperature of about C. to about 200 C., more usually about 180 C. The reaction is continued until the desired acid number is reached or to the point where the viscosity increase of the contents of the reaction zone indicate that the gels tion point is being approached.

The resin, which is a translucent material of color ranging from clear to tan dependent upon the reactants, is controlled to an acid number from about 15 to about 60. This resin is extremely soluble in the hydrocarbon solvents and oxygenated organic solvents commonly used in the surface coating field. The better known of these solvents are methyl alcohol, ethyl alcohol, butyl alcohol, acetone, methylethyl ketone, Cellosolve, benzene, toluene, xylene, and also in mixed solvents such as 60:40 volume ratio of xylenes and butyl alcohol. Also, the resin is distinguished by its property of forming relatively stable dispersions (emulsions) in water; these emulsions may readily be formed by agitating the resin and water at a moderately elevated temperature such as 150 F (650 C.)

The resin may be utilized in its organic solvent solution or Water emulsion to form air-dry surface coatings. Preferably, the solutions contain a cobalt and/ or lead drier to speed up the drying reaction. The various cobalt and lead driers in the paint industry are suitable for this purpose. In addition, the solutions may contain pigments such as titanium dioxide and color imparting bodies permitting the lay down of a film of the paint type.

Even though the solvent soluble resin and Water emulsion forms are particularly useful in the surface coating field, it is preferred that the resin be converted to a Water soluble form permitting the use of Water as the vehicle for a true water solvent, (vehicle) surface coating affording composition.

WATER SOLUBLE RESIN The water soluble resin consists of the resin produced by the reaction of the polycondensation reaction and an alkaline reacting agent. The resin and the agent are reacted until a water soluble resin is obtained. Usually enough agent is used to neutralize the acidity of the resin; less may be used. The amount of alkaline reacting material is most readily determined by following the pH of the aqueous medium. The resin passes into solution substantially completely at a pH of about 5. In practically all instances, the resin will be in a complete solution at a pH of about 6. The use of alkaline agent in excess of that needed to bring all the polyester product into solution is not harmful, at least up to a Water solution pH of about 8. It is preferred to have the aqueous solution somewhat on the acid side or neutral, i.e., a pH of from 6 to 7.

The alkaline reacting agent may be ammonia or alkylamine, or heteroamine or an alltanolamine. Ammonium hydroxide as the aqueous solution containing 20-28% is suitable. The alkyl amines, particularly the lower molecular weight containg not more than 4 carbon atoms in each alkyl group, are suitable. The alkanolam-ines, such as 2-amino-2-methyl-1-propanol, ethanolamine and dimethylethanolamine, are especially suitable. The heteroamines, such as morpholine, pyridine, and piperidine may be used. The type of alkaline reacting material used is determined in part by the characteristics desired in the final water soluble resin; also, by the type of resin product which is to be converted to a water soluble form.

The neutralization reaction is carried out by contacting the resin and the aqueous alkaline reacting medium. It is preferred that it be warm, i.e., maintained in the region of 100-160 F. The two are agitated until the resin has passed into solution. The warm solutions of the water soluble resin are clear liquids usually containing some opalescent appearance; the solutions may be colorless or colored, depending on the particular water soluble resin present.

The water soluble resin behaves in essentially the same manner as the resin when exposed to oxygen or air in that an air-dry solid is formed. These water soluble resins produce solutions containing as much or more than 50 percent by weight of the resin. (The water soluble resins are also soluble in the ordinary oxygenated organic solvents, as well as in mixtures of these solvents with benzene hydrocarbons.)

When a paint composition is to be formed, the resin, the alkaline agent, the water vehicle and pigments may be intermingled simultaneously to obtain the water solvent system in one operation.

A resin, either organic solvent soluble or water soluble, of improved air-dry properties is obtained by heating the resin with a cobalt salt of a fatty acid. For convenience, it is customary to heat an organic solvent soluble resin with the cobalt salt at a temperature on the order of 130220 C. The resin and the cobalt salt are held at this temperature for time such that the air-dry properties of a film formed from the resin is improved relative to the resin which has not been cobalt treated. The times will vary with the particular cobalt salt, the particular resin, and the temperature of reaction of the two. The minimum times may vary from minutes to as much as 60 minutes.

The cobalt may be reacted with any of the fatty acids; the hydrate forms may be used. Cobaltous acetate and cobaltous acetate tetrahydrate are preferred cobalt salts. The amount of cobalt salt utilized will depend upon the particular resin and the air-dry characteristics desired in the final treated resin. In general, the salt is charged to the reaction Zone in an amount of 0.05-0.5 weight percent, calculated as cobalt metal, and based on the resin charged.

ILLUSTRATIONS Typical resins of the invention are set out hereinbelow. Also, paint compositions prepared from these resins using water as the vehicle have been prepared and the air-dry property of films produced therefrom are set out.

Resin 1 16.2 grams butyl carbitol (0.10 mole), 26.6 grams linseed fatty alcohols (0.10 mole) and 35.0 grams 3,3,4,4- benzophenone tetracarbo xylic acid (0.10 mole) were heated together for 2 hours at 127-140 C. and then at 170-175" C. for 1 hour and 45 minutes. 49.6 grams dis tilled soya monoglycerides (0.14 mole) were then added and the charge was heated for a additional 7 /2 hours at 170-l75 C. to give a brown viscous resin with an acid number of 48.6.

30.0 grams of the resin were dissolved in a solution of 2.30 grams Z-amino-Z-methyl-l-propanol in 120 ml. of distilled water. 2.50 grams cobalt drier (containing 6% by weight of cobalt) were added, followed by 27.0 grams of titanium dioxide. The film dried tack free after 45 minutes to 1 hour on wood. On glass minutes were required for the coating to dry tack free. Second films were applied successfully after 4 hours drying of the first coat. After 24 hours the films showed good resistance to water by the finger rub test. After 7 days drying very tough hard films resulted. Additional drying time gave coatings having a hardness that can only be adequately described as ceramic-like.

Resz n II To 16.2 grams butyl carbitol (0.10 mole) and 26.6 grams linseed fatty alcohols (0.10 mole) heated to 45 C. were added 21.8 grams of pyromellitic dianhydride (0.10 mole). The charge was heated to C. in 17 minutes and held at 110118 C. for 95 minutes. 49.09 grams (0.14 mole) of distilled soya monoglycerides were added and the charge was heated to C. in 20 minutes. The resin was cooked for 8 hours at 1704175 C. to give a viscous fluid resin with an acid number of 37.1. This resin was converted to a paint in the following manner:

30.0 grams of the resin were dissolved in a solution of 1.77 grams 2-amino-2-methyl-l-propanol in 90 ml. distilled water. 2.50 grams Cyclodex cobalt drier and 27.0 grams titanium dioxide LW grade from duPont were added. The paint dried tack free in 2% to 3 hours and through dried overnight. It passed the finger rub test for water resistance after 24 hours. After 7 days, the coating was not so hard or tough as that obtained from Resin 1 and remains too soft after months of drying to be useful as a protective coating.

Thus having described the invention, what is claimed 1. A resin having air-dry properties when formed into a surface coating film, which resin consists essentially of the polycondensation reaction product of (A) (i) a tetracarboxylic acid having the configuration (11000) (00011), wherein x is an integer from 1 t0 3, y is an integer from 1 to 3, and x and y equal 4; n is an integer from 0 to 1 and Z is selected from the class consisting of CO, and alkyl containing from 1 to 5 carbon atoms, a polyalkylene (ii) glycol monoalkyl ether containing from 2 to 8 ether groups, each alkylene unit containing from 2 to 3 carbon atoms and the allcyl group containing from 1 to 8 carbon atoms, said acid and said ether being present in the respective mole ratio of l:0.35l.0 and (iii) a polyethenoid fatty alcohol containing at least 6 carbon atoms, said "acid and said fatty alcohol being present in the respective mole ratio of l:0.01.65, the sum of said ether and said alcohol being not more than 2 moles per mole of said acid, with (B) a material affording on the average of about two hydroxyl groups per molecule which material is selected from the group consisting of (a) the hydroxyl group containing ester of a polyethenoid fatty acid containing at least about 10 carbon atoms and a polyhydric paraflinic alcohol containing 3-4 hydroxyl groups, (21) the alcoholysis product of a drying fatty oil and a polyhydric paraffinc alcohol containing 3-4 hydroxyl groups and (c) mixtures thereof, said material being charged in an amount such that an excess of hydroxyl groups over the theoretical requirement is present to an extent not less than about 0.5 mole and not more than about 1 mole of hydroxyl groups per mole of acid charged, which resin is charactertized by an acid number of about 1560 and air-drying properties when exposed to the atmosphere at ordinary temperatures in the form of a surface coating film.

2. The resin of claim 1 wherein said ether is diethylene glycol monobutyl ether.

3. The resin of claim 1 wherein said material is the monoglyceride of linseed oil fatty acids.

4. The resin of claim 1 wherein said material is the alcoholysis product of linseed oil and pentaerythritol.

(HOOC)y (COOK),

wherein x is an integer from 1 to 3, y is an integer from 1 to 3, and x and y equal 4; n is an integer from to l and Z is CO, (ii) a polyalkylene glycol monoalkyl ether containing from 2 to 8 ether groups, each alkylene unit containing from 2 to 3 carbon atoms and the alkyl group containing from 1 to 8 carbon atoms, said acidic member and said ether being present in the respective mole ratio of 1:O.351.0 with (iii) a polyethenoid fatty alcohol containing at least 6 carbon atoms, said acid and said fatty alcohol being present in the respective mole ratio of 1:0.0-1.65, the sum of said ether and said alcohol being not more than 2 moles per mole of said acid, with (H) a material afiording on the average of about two hydroxyl groups per molecule which material is selected from the group consisting of (a) the hydroxyl group containing ester of a polyethenoid fatty acid containing at least about 10 carbon atoms and a polyhydric paraffinic alcohol containing 3-4 hydroxyl groups, (17) the alccholysis product S or" a drying fatty oil and a polyhydric paratfinc alcohol containing 3-4 hydroxyl groups and (0) mixtures thereof, said material being charged in an amount such that an excess of hydroxyl groups over the theoretical requirement is present to an extent not less than about 0.5 mole and not more than about 1 mole of hydroxyl groups per mole of acid charged, Which resin is characterized by an Acid Number of about 15-60 reacted with (B) an alkaline agent selected from the group consisting of ammonia, alkylamines, heteroamines and alkanolamines said water soluble resin having air-drying properties when exposed to the atmosphere at ordinary temperatures in the form of a surface coating film.

8. The resin of claim 7 wherein said ether is diethylene glycol monobutyl ether.

9. The resin of claim 7 wherein said material is the monoglyceride of soya oil fatty acids.

10. The resin of claim 7 wherein said material is the alcoholysis product of linseed oil and glycerol.

11. The resin of claim 7 wherein said acid is 3,3,4,4- benzophenone tetracarboxylic acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,048,778 Brubaker et al July 28, 1936 2,870,102 Van Strien Jan. 20, 1959 2,939,863 Mikeska et a1 June 7, 1960 FOREIGN PATENTS 65,650 France Oct. 2, 1953 

1. A RESIN HAVING AIR-DRY PROPERTIES WHEN FORMED INTO A SURFACE COATING FILM, WHICH RESINS CONSISTS ESSENTIALLY OF THE POLYCONDENSATION REACTION PRODUCT OF (A) (I) A TETRACARBOXYLIC ACID HAVING THE CONFIGURATION 